[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20190710165053.cjt7qs7kx5fwu3d4@willie-the-truck>
Date: Wed, 10 Jul 2019 17:50:54 +0100
From: Will Deacon <will@...nel.org>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>, tglx@...utronix.de
Subject: Re: [PATCH] locking/mutex: Test for initialized mutex
On Wed, Jul 03, 2019 at 11:21:26AM +0200, Sebastian Andrzej Siewior wrote:
> An uninitialized/ zeroed mutex will go unnoticed because there is no
> check for it. There is a magic check in the unlock's slowpath path which
> might go unnoticed if the unlock happens in the fastpath.
>
> Add a ->magic check early in the mutex_lock() and mutex_trylock() path.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
> Nothing screamed during uninitialized usage of init_mm's context->lock
> https://git.kernel.org/tip/32232b350d7cd93cdc65fe5a453e6a40b539e9f9
>
> kernel/locking/mutex.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
> index 0c601ae072b3f..fb1f6f1e1cc61 100644
> --- a/kernel/locking/mutex.c
> +++ b/kernel/locking/mutex.c
> @@ -908,6 +908,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
>
> might_sleep();
>
> +#ifdef CONFIG_DEBUG_MUTEXES
> + DEBUG_LOCKS_WARN_ON(lock->magic != lock);
> +#endif
Why do we need to check this so early, or could we move it into
debug_mutex_lock_common() instead?
Will
Powered by blists - more mailing lists